This proposal is a pilot study for a large-scale prospective adoption study of behavioral development. The adoption design is the most powerful strategy to untangle genetic and environmental influences in development. Moreover, combined with extensive environmental assessments, the adoption design can definitively isolate environmental influences and genotype-environment interactions, and it can assess genotype-environment correlations and test the direction of environmental effects. Biological parents will be tested on a battery of behavioral tests that measure the major factors of cognition and personality at two adoption agencies. Forty of their adopted children will be tested in their adoptive homes at one year of age on the motor and mental tests of the Bayley Scales of Infant Development and the Infant Behavior Record and the Piagetian-based Hunt-Uzgiris ordinal scales. Naturalistic, time-sampled observations of the adopted children's behavior and environment will also be included. In addition to the observational environmental assessments, interview data will be collected using the environmental measures of White and Watts and Caldwell's Inventory of Home Stimulation. The adoptive parents of these forty children will be tested with the same tests as the biological parents. This pilot study will provide the first multivariate analysis of environmental and genetic influences in early behavioral development using the adoption design. It will also lay the foundation for a large-scale research effort by establishing a "data bank" on 200 biological mothers and 100 biological fathers.